Due to technological advancements, the growing popularity of electronic products, the integrated circuit (IC) chips with powerful functions are constantly being introduced. In these electronic products, such as communication devices, notebook computers and household appliances, etc., utilizes the DC motor driver chip with small size and high efficiency, and commonly used in computer CPU, CD-ROM drive and hard disk, etc.
Generally, the drive of the DC motor utilizes a Hall element to sense the motor rotor position, such that the driver can transmit the appropriate commutation signal to rotate the motor rotor. The commutation will directly affect the performance of the overall motor driving system, so that the accuracy of the Hall element sensed the changes in the external magnetic field should be increased to promote the accuracy of the commutation control.
However, after motor driven, Hall element would be influenced by the stress generated on the IC chip surface due to the IC packaging or due to manufacturing changes when subjected to wafer processing (for example, the doping concentration or doping depth is inconsistent) and the external ambient temperature, the Hall element will generate an unexpected offset voltage to cause reliability of the Hall element is decreased, so that the Hall element cannot point out the rotor position accurately to communate. Thereby, the noise will be introduced by the motor rotation and the use of comfort also would be influenced.
According to aforementioned, the unexpected offset voltage is to be eliminated to allow the Hall element that can sense the changes in the external magnetic field accurately and can point out the rotor position correctly and to drive the corresponding communation of the motor to increase the reliability of the communation, and the motor rotation noise is reduced that is the problem should be solved by the present invention.